Metaphysics and The Copernican Revolution: An Essay
       ___________________________________________________
                        Lynette Gelinas

                        Department of Physics
                        University of New Hampshire
                        Durham, New Hampshire 03824
                        ljg@curie.unh.edu

                        (received November 30, 1994)

	Metaphysics is a difficult subject to comprehend, much less
write about.  In trying to find an appropriate topic to write about for
this journal, I found myself wondering about the nature of metaphysics
and science.  I discovered two good books on the subject,  Jennifer
Trusted's "Physics and Metaphysics" and "Novelties in the Heavens" by
Jean Dietz Moss.  Confronted with what turned out to be too much
material, I chose to concentrate on the Copernican revolution, but even
this narrow subject proved too complex.  So I have turned my focus back
toward metaphysics and science, hoping to use elements of the Copernican
revolution to illustrate these difficult concepts.

	Nicolas Copernicus was born in 1473 to relatively wealthy
parents.  He attended the prestigious Cracow University and by age 27 he
was considered a "gifted mathematician, lecturing to colleges in Rome."
[1]  As a mathematician he was also interested in astronomy, and soon set
about the task of revising Ptolemy's "Almagest".  The "Almagest"
contained  complex astronomical tables and a description of the
physical model of the cosmos.

	Ptolemy based his model on both observation and Aristotle's
principles;  therefore the earth must be at the center of the universe,
with the sun, moon and planets embedded in concentric crystalline
spheres, the outermost sphere being the sphere of fixed stars.  To fit
this model to the apparent motion of the heavenly bodies, Ptolemy
devised a complicated scheme of epicycles, equants, and non-uniform
circular motion.  He had to offset the rotational axes of the heavenly
spheres from that of the earth's axis and incorporate epicycles to
account for the retrograde motions of the planets. [2]  Ptolemy calculated the
appropriate parameters to fit his models, but as he considered the model
complete he published only his results, feeling the calculations to be
tedious and their repetition unnecessary.  Ptolemy lived from (90 -168 AD).
Over the years his "Almagest" had been amended to "save the
appearances".  Copernicus was to follow this tradition of revisions.

	In 1514 Copernicus published the brief "Comentariolus" proposing his
heliocentric theory, with promises of more complete calculations to
follow.  Just before his death in 1543 he published "De Revolutionibus
Orbium Coelestum Libri VI", his comprehensive cosmological model.  
He proposed the diurnal rotation of the earth about its axis, and the 
revolution of the earth and all the planets about the
sun, which he proposed to be at the center of the universe.  The sphere
of fixed stars remained where Ptolemy had left it.  Although in later
years Copernicus concentrated on astronomical observations, his initial
work was based entirely on Ptolemy's observations in the "Almagest".  [3]
His intention was only to improve upon the astronomical calculations so
important to navigation and determining the dates of the equinoxes and
Easter Sunday.  And although he personally believed in the actual
physical representation of his model he was careful to present it as a
mathematical tool, not the physical reality.  In fact, he was never able
to prove his model through astronomical observation;  the stellar
parallax and phases of Venus predicted by his model eluded him.  It is
notable that because of these difficulties and his method of
presentation of his model he was never considered a heretic to the
Church in his lifetime.  Copernicus had been dead for nearly 70 years
when the Church put "De Revolutionibus" on the list of books forbidden
to Catholics.

	Those of us accustomed to living in a heliocentric system
understand that Copernicus' model was infinitely better than Ptolemy's.
Our system of beliefs has trained us to verify models through
observation and to strive for the simplest explanation of physical
phenomena (Occam's Razor).  Incidentally, William of Occam lived from
1300 -1349, long after Ptolemy!  How are our metaphysical beliefs
different from Ptolemy's, and had they changed in Copernicus' time?

	We will start with a brief summary of Medieval philosophy.
Every effect must resemble its cause, and since God was the ultimate
cause of everything the entire cosmos must bear traces of the Divine
hand.  Scholars held that satisfactory explanations of events had to be
in terms of a purpose, teleogical explanations.  True knowledge came
from Divine enlightenment, Scripture and ancient texts;  human senses
were a poor fourth.  The study of science or natural philosophy involved
the study of the natural world and examination of Scripture and ancient
texts, for the world revealed God's concern for man and His purposes.  [4]
Ancient texts were, of course, nearer to the truth because they were
written soon after the Fall of Adam and Eve.  These ancients most likely
had memories of direct contact with God after the Fall;  indeed there
has been a steady moral decline since then!

	Some of these ancient and religious beliefs still figure into
our scientific pursuits:

	"God created the world and maintains a smooth running of the
cosmos, therefore there exists an orderly succession of events which 
may be accounted for in causal laws.  
	God is good and He would not deceive mankind, therefore human sense
experiences can give reliable information on created world.
	God created Man in His own image, therefore humans are capable 
of reasoning from sense experience and are capable of discovering the 
causal laws ordained by God." [5]

These are important metaphysical beliefs, with or without a deity.  For
example, is it not amazing that we consider most people's senses 
equivalent to ours?   Do you see the same "red" that I do?  This 
could account for some folks' poor fashion sense!

	Not only was the influence of God and Scripture important to
Copernicus and others at this time, but the physical theories of
the time also affected their opinions.  It has been said that if a 
man in 1500 believed that the earth moved around the sun, there's 
no telling what else he might believe!  As an example let us look 
at two of Copernicus' postulates:  that diurnal rotation of the 
earth and the rotation of the earth around the sun.  In 1500 it was 
believed that the earth was at the center of the universe, immobile.  
This was readily confirmed by the fact that objects fell at right 
angles to the earth's surface, for they sought the center of the universe.  
The idea that the earth spun was absurd.  If the earth rotated on 
its axis violent forces would arise at its surface causing objects 
NOT to fall at right angles to the earth's surface. [6]
Birds flying east would make no headway, and clouds would be seen to
drift westward, which they certainly did not.  Inertial motion was
unknown to people in 1500.  Modern folks experience its effects daily
when a car or train stops suddenly and everything lurches forward, but
nothing moved very fast in 1500.  [7] It was common knowledge that an object
thrown vertically up from a moving cart would fall to the ground, the
cart having moved out from under it.  A bumpy cart was not conducive to
these types of experiments!  Surprisingly, we accept a similar
phenomenon today:  that the speed of light is a constant, regardless of
the motion of the source.

	More telling than this is Copernicus' defense of his thesis.  He
used Aristotle's principle that the natural motion of heavenly bodies was
uniform circular motion, and having relegated the earth to the heavens
he felt justified in claiming that this natural motion would have no
unnatural side effects.  He also claimed that because water and air were
two of the earth's four natural elements, the others being fire and
earth, they would move as a part of the earth, therefore the clouds
should exhibit no unusual movement.  Copernicus had only a vague notion
of gravity as we understand it today, for he defined "gravity" as an
urge objects possessed to be one with an entity.  He proposed that the
other heavenly objects probably had their own "gravity". [8]

	Ptolemy had placed the earth at the center of the universe
because of its immense weight;  if the earth were allowed to move it
would immediately fall from the heavens, leaving people and objects
stranded in mid-air!  Again, Copernicus resorted to the principles of
Aristotle, claiming that the only natural motion of the heavenly bodies
was circular.  The earth could not fall from the heavens because
vertical motion was natural only to the elements of the earth.  Besides,
Copernicus had moved the earth just a little from the center of the
universe, as compared to the sphere of fixed stars.

	Now, it seems that I've just been telling a good story here, so
where is the metaphysics?  It's in the belief systems.  Our impermanent
belief systems.  The Copernican revolution really began with Galileo,
since he helped confirm the physical model.  Einstein proposed another.
Are we to constantly revise our universe?  Metaphysics and Physics have
an interesting relationship;  one cannot exist without the other.  Our
metaphysical beliefs influence our physical world-view.  Observations of
the physical world can confirm or refute our metaphysical beliefs.  In
essence, each evolves with the help of the other.  So, have I written
about what I intended to?  Well, yes and no.  I still haven't explained
metaphysics very well; few people can.  But I think I have shown that
metaphysics isn't just "beyond physics", it's in front of it, behind it,
intertwined with it.  It's the question that every physicist asks:
			"WHY?"

	
[1] Jennifer Trusted,  "Physics and Metaphysics"  (Routledge, Chapman and
	Hall, Inc., NY.  1991) p. 24

	
[2] Jean Dietz Moss,  "Novelties in the Heavens"  (University of Chicago
	Press, Chicago, 1993) p. 55

[3] Jennifer Trusted, p. 24

[4] Jennifer Trusted, p. 14

[5] Jennifer Trusted, p. xi

[6] Jean Dietz Moss, p. 56

[7] Jennifer Trusted, p. 30

[8] Jean Dietz Moss, p. 56